Note 3 - Investments and Fair Value Measurements - Summary of Unaudited Financial Statements of Affiliate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 30, 2019
Company share of adjusted net loss at 20.58%	$ (1,043)
Equity investment in affiliate	4,865
Virtual Power Systems [Member]
Current assets	3,739
Non-current assets	4,306
Total Assets	8,045			$ 2,500
Current liabilities	396
Non-current liabilities	2,725
Stockholders' equity	4,924
Total liabilities and stockholders' equity	8,045
Revenues	154
Operating loss	(5,151)
Net loss	(5,151)
Foreign currency translation adjustment
Comprehensive net loss	(5,151)
Add back excluded acquisition intangible amortization, net	86
Adjusted comprehensive loss	(5,065)
Company share of adjusted net loss at 20.58%	(1,043)
Equity investment in affiliate	$ 4,865